Dental chair



A. J. MAY

DENTAL CHAIR April 9, 1929.

Filed Nov. 20, 1925 4 Sheets-Sheet Rm NW Q llfl/ENTOR. 146251 L/j/ J\ 12.5 ATTORNEY 4 m, Q Jr/l 4 April 9, 1929. A. J. MAY 1,708,450

DENTAL CHAIR Filed Nov. 20, 1923 4 Sheets-Sheet 2 \MW\ 1 Am 4.

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; BY- k j /z: A TTORNEY A. J. MAY

DENTAL CHAIR April 9, 1929.

Filed Nov. 20, 1925 4 Sheets-Sheet INVENTOR.

LLISATTORNEY 4 Sheets-Sheet 4 INVENTOR. fldzzlra r [aEzATTORNEY v wwww A. J. MAY

DENTAL CHAIR April 9, 1929.

,Filed NOV. 20, 1925 Patented Apr. 9, 1929.

PATENT OFFICE.

UNITED STATES ADAlVI J. MAY, OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

BITTER DENTAL MEG. (30., OF ROCHESTER, NEW YORK, A CORPORATION OF DELA- WARE.

DENTAL CHAIR.

Application filed November 20, 1923. Serial No. 675,963.

This invention relates to adjustable supports of the variety adapted for use for example, with dental, surgical, barber's and other chairs. for supporting and adjusting the same to ditterent elevations, one object of the invention being to provide improved apparatus of this character having a simple, compact and efiicient "form of construction capable of being operated by a self-contained electric or other motor of small. size and power. Another object is to provide a motor actuated device of this variety having an advantageous form of control means including devices operating automatically to stop the movement of the parts when the latter reach the limits of their range of adjustment. A further object is to provide such an apparatus constructed that the relatively movable, weight sustaining parts engage each other by means of rolling bearing members to substantially eliminate friction therebetween and reduce the power required for operation. Still a further object is to provide a mechanism of this type having a driving connection with its motor of such a character as to lock the parts against operation eXcept when driven by the motor.

To these and other ends the invention resides in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Fig. 1 is a central sectional elevation of apparatus embodying the present invention;

2 is a detailscctional view on the line 2 2'" in Fig. 1;

Fig. 3 is a sectional elevation in a plane at right angles to Fig. 1 or on the line 3 3 in Fig. 9, and showing the parts in a different position;

Fig. 4 is an enlarged sectional detail of an .ignutand spindle means;

. 5 is a plan .view of the same; 6 is an enlarged central sectional elevation of actuating parts shown in Fig. 1;

Fig. 7 is a sectional detail on the line 7 a in Fig. 6;

Fig. 8 is an elevation of a control means;

Fig. 9 is a plan view partly broken away and partly in section on the line 9 9 in Fig. 1, and

Fig. 10 is a similar view partly in section on the line 10"10 in Fig. 1.

Similar reference numerals throughout the several views indicate the same parts.

The embodiment of the invention disclosed herein, by way of illustration of the principles involved, comprises, preferably, a base portion, indicated generally at 20, Figs. 1 and 3 on which are carried vertically adjustable parts the uppermost of which provides a support 21 for the chair body proper. The base has a substantially horizontal bottom flange 22 of ample diameter adapted to reston and be secured to the floor. Formed integrally with this flange is an upwardly extending cylindrical portion or sleeve 23 in the upper half of which are circumteren tially spaced pairs of bearing rollers 24. with the rollers of each pair arranged one above the other, each roller being rotatably support-- ed by trunnions journaled in suitable brackets on the sleeve as shown. These rollers serve to guide the vertical movement within the sleeve 23 of an intermediate sleeve 25 of the generally oval transverse shape shown in Fig.9 and formed externally at the center of its longer sides with tracks 26 for the rollers 24 so disposed that the latter serve also to prevent rotation of the intermediate sleeve. The latter is preferably though not necessarily of substantially the same length as sleeve 23 of the base within which it telescopes and carries within it peripherally spaced pairs of rollers 27 arranged and rotatably sup-' ported substantially as described above in connection with the base sleeve 23. Rollers 27 engage tracks 28 on a substantially cylindrical sleeve 29 depending from the chair support 21 and guide the latter for vertical adjustment telescopically within the intermediate sleeve 25, while holding it against rotation. The support sleeve 29 is preferably about equal in length to sleeves 23 and 25. The upper end of sleeve 29 rotatably engages a depending flange 30 fixed to support 21 to which however sleeve 29 is normally clamped by any known or suitable means such for ex- It is apparent from the above descriptionthat the support 21, and its depending sleeve 29 are guided for elevational movement within the intermediate sleeve 25 and the latter in turn within the base sleeve' 23 and means are provided for effecting such movements, which will now be described.

The base has a: bottom" plate 32" secured thereto as by means of dowels 33 and screws 34 and formed centrally with a hearing. recess 35 in which is rotatably mounted at its lower" end' a vertically extending" screw threadedspindl'e36i The lattercarries at its lower end agear 37 forming'part' eta drive transmitting connection with an electric 1 iotor' presently to be described, for rotating the spindle in either direction to raise and lower the support respectively. Spindle 3.6

extendsthrough a' cooperating". internally threaded part 38-, in the present instance in.

the form of a nut fixed asrby means of set screws 39' in a seat in a ring 40 fixed by screws41 concentrically in the lower end of sleeve 25, the threads of the nut being connected with those of the spindle by a plurality-of rolling bearing; members for eliminating friction as hereafter described. It is apparent therefore that rotation of'spindle 36 ino'n'e, direction orthe other serves toraise or lower the intermediate sleeve.

The means for efl'ecting elevationa'l movement oft-he support relative to the intermediate sleeve comprises, preferably, an inner sleeved? surrounding spindle 36' and provided at its lower end with a thrust bearing 43., of the-ball and race variety, of nut 38-, Figs 1 and 6, the sleeve being thus rotatably carried by the intermediate sleeve 25-and-movingverti'cally with the latter; In, ner sleeve 42is'rotat'ed by a slidingform of connection with spindle 36 comprising rollers 44 rotatably carried in heads 45 set into dovetailed slots inthe-upper end of the spindie as shown" also in F 6 and 7. These rollers travel in vertical slots 46 formed in the inner sleeve 42" and the latter is thus rotated by'the spindle, while freely adjustable vertically with the intermediate sleeve 25 by which it is carried.

The rotatable inner sleeve 42 has an actuating connection with support 21' comprising inthe present instance threaded part 47 preferably in the form of a nut fixed as by means-of dowel pins 48 to the top of a can ills'ecured one the upper end of sleeve h which'thus rotates the nut 47 whenever spinon the upper end by the rota ion of spindle 36. it is noted that the support not only acquires the elevational movement impart-ed to intermediate sleeve 25 through the-cooperation of spindle 36 and nut 38 but also the additional elevational movement-'relative to the intermediate sleeve imparted by the c operation with the support spindle 50; of the nut wiich is rotated by spindle In other words the int rmediate sleeve and support have ditieren'tialelevational mo'vement relative the baseso that the support is afforded a movement of substantial and velocity 1 y parts which furthermore telescope compactly'one within another.

The construc ion oi? the spindle and nut means for eliminating friction therebetween is best shown in Figs. l, 5 and 6, from which it may be seenthat the adjaeentthreadshave intervals therebetween of substantially semicircular profile adapted to rece; e a plurality of. rolling bearingmembers in the form, in this instance, of balls 52, each of which rolls in engagement with both the spindle and nut so that the latter have, substantially a frictionless rolling bearing on each other; The halls fill the threaded intervals within the nut and a continuous channel 53' is formed in the nut with its ends connectedwvith the respective ends of the thread of the latter for receiving the balls as they roll out of the nut thread at one end and for supplying the same to the v nut thread at its opposite end The end of the nut thread is provided with a finger 5% for preventing the balls from escaping from the nut and for directing the same into the channel so that the balls are retained within the nutand constantly supplied to the thread of the latter as it moves up and sown the spindle. Substantially the same construction is employed in'the second or upper nut -17 and the various weight supporting parts of the apparatus thusengage one another through rollingbearingmembers, with the'result that triction'al resistance is substantially eliminated and the various parts move smoothly and quietly upon each other andwith a minimum of'wear. v

' The means for rotating; the spindle 36-co1nprises the gear 3? fixed on the lower end of the latter and having a thrust bearing on the base plate 32, of the balland race variety, shown in Fig. 6. li l'eshing with gear 37 is a gear 56 rotatablysupported on the base plate a and meshing'in turn with a gear also rotatablysupported on the plate and fixed on the lower end of an upright shaft 58 journaled at its upper end in a frame member 59. Fixed on the upper end of the shaft is a worm wheel 60 driven by a worm 61 on the shaft 62 of a driving motor 63 supported on an extension 64: of the flange. Motor 63 is preferably of the series wound reversible type for either raising or lowering the support and it is to be noted that its connection with the adjustable parts comprises the worm and worm wheel described above which serve as an automatic lock for holding the parts against movement except when actuated by the motor.

The latter is controlled by a combined pedal and automatic device illustrated in Figs. 8 and 10 and comprising an operating controller 65 mounted in a recessed portion 66 conveniently located in the vertical wall of the base adj acent its bottom. The controller has'a stationary supporting plate 67 provided with a plurality of concentric arcua-te contacts 68 to 72 inclusive fixed on the plate and insulated from each other. The plate rotatably supports at its center a spindle 7 4 having fixed'thereon a hub carrying oppositely extending arms 75 and'76, each of which is provided on its under side with conducting strips77 as shown for connecting radially spaced, adj acent. pairs of the contacts 68 to 72. Fixed to the hub also are oppositely extending pedals 7 8 and 7 9 and a leaf spring 80, supported at its center in any suitable manner, has its ends engaged with the pedals respectively for returning the latter to the neutral position shown in Fig. 8. Pedals 7 8 and 7 9 are moved by the operator for either elevating or lowering the chair as more fully explained hereafter.

Supported on the inner surface of the wall of the base is a bar 81 on which are mounted a pair of switch means 82 and 83. Each of these comprises an arm 84; pivotally supported at 85 on bar 81 and carrying a contact piece 86 for engagement with one or the other of a pair. of fixed contact points 87 and 88, the switch arm being stopped in position over one or the other of these contact points by stop pins 89. The switch arms are engaged and swung by a finger or pin 90 projecting from the elevating sleeve 25, the switches being located adjacent the desired limits of movement of the finger so that the latter raises the arm of the upper switch and depresses the arm of the lower switch as the elevating parts reach their upper and lower limits of movement, respective-y. Springs 91 normally retain the switch arms in their opposite positions. The contact points87 of each switch are connected by a conductor as shown with contact 69 of the controller and the other contact of each switch is connected with the contact 70. Contact 68 is connected by a conductor 92 with the field of the series wound motor, theother terminal of which is connected with one side of the power line. Contact 71 is connected by a conductor 93 with one armature terminal of the motor while contact 72 is connected by a conductor 94 with the other armature terminal. The other side of the line is connected to each of the switch arm contact pieces 86.

It is evident from the above described de vices and circuits that when the pedals 7879 are in the neutral position shown, the motor circuit is open and the apparatus is stationary. \Vhen the chair elevating parts occupy an intermediate position, movement of the controller pedals in one direction connects the motor with the line in such a manner that the chair supportis elevated as long as the controller pedals are held in such position or until the upper switch arm 84: is thrown by the means described to its uppermost position whien breaks the circuit and stops the motor. In this extreme position the motor circuit can only be closed by moving the controller pedals in the opposite direction for starting the support downwardly, in which latter position the motor circuit, of course, is connectedwith the line in a reverse sense. If the chair supporting parts are moved by the controller to their extreme lower position, the lower switch is operated in a similar manner to break the circuit so that the motor can then be connected with the line only in sucn a sense as to raise the chair.

The invention thus comprises a relatively simple and etfectivepedal control means by which the motor may be quickly started in either direction for raising or lowering the parts and quickly stopped in a desired position of the latter, a brake means of known variety being provided for the motor. if desired for stopping it more rapidly. In any stationary position of the parts they are securely retained against movement by the worm and worm wheel driving connection with the motor until the latter is again actuated. Vhen the elevating parts reach either limit of movement they are stopped by the automatic l mit switch means described. which dispose the circuits in such a way that the pedal controller is then effective only fol-moving the parts in the opposite direction.

The operation of the apparatus has been fully disclosed in connection with the above description of its construction and it is evident that the latter is simple and practical in character comprising comparatively fev parts so designed and arranged and connected by rolling bearing members as to reduce frictional resistance to a minimum. The apparatus is thus capable of being efficiently ope 'ated by an electric motor of small size and power consumption} The parts are furthermore of a strong and durable nature having a pleasing simplicity of appearance. The apparatus is furthermore controlled by a con venient and fool proof device by means of which the support for the chair or other part may be quickly,smoothly and quietly raised or lowered toany desired position wltlllll' ample range of movement.

. 1 claim as my invention:

1. In apparatus oi'ithecharacter described, the combination-of a base, a support guided for elevational movement on said base, cooperating parts comprisingascrew and a nut on said base and support each: provided with. a helical ball race, a plurality of ball members between said cooperating parts each rolling: in engagen'rent with said races and forming the sole connection therebetween to provide a substantially frictionless bearing, one of said. parts having a vertical bypass permitting the balls to dropby gravity to the bottom of the race, a: detachable finger at the top of the nut adapted to deflect the balls into said 'by-pass, and means for. actuating'said parts to raise and lower said support. a

2. In apparatus of the character described, the combination: of a base, a support guided for elev'ational movement on said base, co-

1 operating spindle and nut means on saidbase and support for elevating the latter onsaid base and each provided with a" helical ball race, and a plurality of ball members-each engaging said races and forming the: sole con-' nection between said spindle and nut to provide a substantially frictionless bearing therebetween, said nut having a vertically disposed pasage leading from the top of the race whereby the balls are adapted'to drop by gravity to the bottom of the race and a detachable finger at the toprof the nut adapted 'to direct the balls into said passage.

In apparatus of the character described,

the combination of a base a su J TONI-incl .or-

tion guided for el'evational movement relative to said base, a spindle rotatable onsaid base and provided with a helical ball race, a nutcarried by said portion for cooperation with said spindle and also'provided with a helical ball race, a plurality of ball members each engaging said races and forming the sole connection between the said spindle and nut to provide a substantially frictionless connection therebetween, said nut having a vertical passage permitting the balls to drop by gravity from the top to the'botto'm of the race, a detachable'finger at the top of the nut lo-r deflecting the balls into said passage and means for rotating saidspindleto elevate said supporting portion. 7

4. In apparatus oft-he character described, the combination of a base having-a rotatable threaded part, a portion provided with means guiding the same for elevational movement without rotation on saidbaso, a threaded part on said portion cooperating with said thread-, ed'base part,a sleeve rotatably carried by said portion about said threaded base part, a sliding connection between said threaded base part and sleeve for rotating the latter, a

threadedpartfi-Xed to said sleeve, asupport and athreade'd part-fixed to said supportand cooperating-"withsaid threaded sleeve part. 5.= In apparatus of the character described, tlre'combi nation of a base havingan externally threaded, hollow, rotatable spindle, a portion provided with means guiding the same for elevational movement without rotation on said base, a threaded part on said portion: cooperating with said spindle, a sleeve rotatably carried by said portion about said spindle, a connection between said spindle and sleeve adjustable longitudinally thereof for rotating the sleeve, athreaded part fixed to: said-sleeve, a support a threaded spindle fixed to. said support for cooperation with said sleeve part and positioned for reception in said hollow base spindle, a plurality oi ball bearing members connecting the threads of each of said spindles withfi-ts correspond ing threaded part, and means for rotating said base spindle. I i i y 6. In a device of thecharacter described, tlrecombination of aba-se having an upward ly'exterrding sleeve,-an intermediate sleeve slidablie longitudinally in said base sleeve and having a threaded part fixed thereon, va su-pport having a sleeve slidable longitudinally in said intermediate sleeve, means guiding said intermediate and support sleeves and preventing rotationthereoflan inner sleeve rotatably carried by said intermediate sleeve: and h avingq a threaded: part fixed thereon, a threaded spindle fixed to said'supp'ort for cooperation with' said inner sleeve part, a threaded spindle rotatable on said'base for cooperation with said intermediate sleeve part and engaging said inner sleeve to rotate the same, and ball bearing members connecting the threads of each spindle with those of the cooperating threaded part. 7. In apparatus of the class. described, the combination of a; base, a sleeve reciprocally mounted within'the base, a nut fixed upon the sleeve, an. upstanding screw rotatably supported by the base and threadedinto said nut, an inner sleeve disposed within the first mentioned sleeve and-frotatab'ly supported by said nut and adapted to be rotated by said screw, :1; secondnut' connected with the upper end of the innersleeveand adaptedtobe rotated thereby, a screw threaded through said second-nut and projecting downwardly into the inner sleeve, a support carried by the second mentioned screw and including a portion projecting between: and guided by one'oi' the sleeves and means'for rotating the first mentioned screw.

8. Inapparatusof the character described,

the combination of abuse, a rotatable screw relative to each other, a support, a third screw threaded member mounted on said support, a fourth screw threaded member cooperating with said third screw threaded member and movable axially with respect thereto when said third and fourth members are rotated relative to each other said fourth screw threaded member being rotatably mounted on said second threaded member, and means including an anti-friction roller and a surface cooperating therewith for operatively connecting said first threaded member to said fourth threaded member to transmit the rotations of the former to the latter while allowing relative axial movement thereof.

ADAM J. MAY. 

